Analysis: x86 Vs PPC

Gentu writes "Nicholas Blachford (engineer of the PPC-based PEGASOS Platform) wrote a long and detailed article, comparing the PPC and the x86 architectures on a number of levels: performance, Vector processing and Power Consumption differences, architectural differences, RISC Vs CISC and more. The article is up-to-date and so it takes the G5 into account too."

Comments

These arguments are so tired

[uradu]

This isn't the '80s anymore where performance is the most critical issue and we jump platforms every time a faster architecture comes out, since we don't have a large software base anyway. Nowaways software IS the more important aspect, and only relatively few well-heeled, game-addicted geeks are going to jump on the PPC just because it's a fews ticks faster this week, and Jobs winked at them with that very special smile. Given the way this industry goes, IBM/Motorola will sit back again, wipe the sweat off their foreheads and take a breather, and before you know it, Intel/AMD will have a faster processor again.

If you have x-platform software that will compile painlessly on either architecture, go for it, switch with each faster chip. But for most others, I doubt performance rants like these will make much of a difference. After all, how many Mac users switch to the PC just for the performance during those stretches when the PC has the upper hand?

Truly suprising colnclusion, OR NOT!

[pbox]

Nicholas Blachford (engineer of the PPC-based PEGASOS Platform) says that the PPC is better than x86.

What an unbiased opinion. Maybe we should really hear the other side too. I like the article for the wealth of info, and we all know the shortcomings of the x86 platform, but the conclusion seems to be biased.

Or is it just me?

Re:Truly suprising colnclusion, OR NOT!

[stevew]

Yep, and he is still stuck back in the 80's with his RISC vs CISC arguments. He says that internally they pretty much look the same (which they do) but they're some how different because RISC is easier to make happen.

Well - today's RISC's aren't very RISCy anymore. ;-) Todays CISC's have the same aspect. The machines have all migrated to simpler cores running VERY fast, but then tagging on features like predictive branching, out-of-order execution, etc.

An example of where the guy goes wrong is in his discussion of the compilers. What he fails to understand is that one BIG reason that the Intel compiler is better than GCC is that the same kinds of compiler optimization that accounts for how the hardware schedules things work for both the PPC and the Intel architecture. This has been true since the original entry of the MIPs architecture for goodness sake. Intel KNOWS what the hardware is going to do, and built those smarts into the compiler! You can do the same thing for the PowerPC by the way..not saying you can't.

Nuff said - it was an interesting article but bowed to much towards RISC is Great - All Hail RISC bunch.

[Q] Small & Expensive = CISCRISC?

[4of12]

When Microprocessors such as x86 were first developed during the 1970s memories were very low capacity and highly expensive. Consequently keeping the size of software down was important and the instruction sets in CPUs at the time reflected this.

So I'm puzzled. Perhaps someone can enlighten me on this.

If CISC is particularly appropriate for memory that is

1. low capacity, and
2. highly expensive

why doesn't the same argument apply to CPU's with no main memory per se, but just a good sized L3 cache?

Modern cache memories are, guess what,

1. low capacity, and
2. highly expensive

so it would seem to follow that higher performance could be got by using a CISC model.

Since main memory latency and BW are pretty limiting, I half expect that there's good argument to make very high performance systems live completely inside a large cache.

Re:PPC

[ichimunki]

I think you missed his/her point. If the cost of the more energy-efficient processor exceeds the amount of the money saved on the power bills, the company or household is worse off for buying the more efficient model. In the example, the $37 was no match for the $500 extra expense of the system.

Imagine buying a G5 iMac desktop will save me $50/year in electricity bills, but the system costs $200 more than a comparable x86 machine. Then it takes four years for the energy savings to pay for the added equipment expense. Multiplied over 50 workstations, the effect is the same, only the numbers get bigger on both sides of the equation. Just because those 50 machines will save me $2500 annually, doesn't mean they're necessarily worth $10,000 more up front.

However, the energy assumption is a difficult one to make. Energy costs are volatile, generally only increase, and are not an insignificant variable expense for most businesses-- minimizing that expense is not a bad move.